How Internet Routing Works Step by Step | Generated by AI
Great question! You’re touching on the core of how the internet routes traffic from your device to a destination like google.com. Here’s a step-by-step breakdown of how routing works, using your traceroute example:
1. DNS Resolution
- When you type
google.com, your device first queries a DNS server to resolve the domain name to an IP address (e.g.,142.250.73.78). - This IP is the final destination for your packets.
2. Local Routing Table
- Your device checks its local routing table to decide where to send the packet next.
- For most home networks, the default route is your home router (e.g.,
192.168.1.1). - Your device sends the packet to
192.168.1.1because it’s the default gateway for all non-local traffic.
3. Router Forwarding
- Your home router (
192.168.1.1) receives the packet and checks its own routing table. - It knows that for any IP not in your local network, it should forward the packet to your ISP’s router (the next hop).
- The ISP’s router is usually the first external IP you see in
traceroute(e.g.,14.147.135.206).
4. ISP and Beyond
- Your ISP’s router receives the packet and checks its routing table.
- ISPs use Border Gateway Protocol (BGP) to exchange routing information with other ISPs and networks.
- BGP dynamically updates routing tables to reflect the best path to each destination IP.
- Each router along the path repeats this process: it looks up the destination IP in its routing table and forwards the packet to the next hop.
5. Dynamic Routing Updates
- Routing tables are not static. They are updated dynamically using protocols like:
- BGP (for inter-network routing, e.g., between ISPs)
- OSPF or RIP (for intra-network routing, e.g., within an ISP’s network)
- If a link fails or a better path is found, BGP/OSPF updates the tables and reroutes traffic.
6. Traceroute in Action
- Each line in your
tracerouteoutput represents a router (hop) that forwarded your packet. - The
*means the router didn’t respond (common for security reasons). - The IP addresses you see are the interfaces of routers that responded.
7. Proxy Note
- Your output shows a proxy (
127.0.0.1:7890). This means your traffic is being routed through a local proxy before reaching the internet. - The proxy may alter the path or hide some hops, but the fundamental routing process remains the same.
Summary Table: How Routing Works
Routing Process
| Step | Action |
|---|---|
| DNS Resolution | google.com → 142.250.73.78 |
| Local Device | Sends packet to default gateway (192.168.1.1) |
| Home Router | Forwards to ISP’s router (14.147.135.206) |
| ISP Router | Uses BGP/OSPF to forward to next hop |
| Destination Network | Final routers deliver packet to 142.250.73.78 |
Key Points
- Routing tables are like maps for routers, telling them where to send packets next.
- BGP is the protocol that keeps the internet’s routing tables up-to-date.
- Traceroute shows the path your packet takes, hop by hop.
Would you like a deeper dive into any specific part, like BGP or how ISPs manage routing?